This application is based on and claims the benefit of priority to Korean Patent Application No. 10-2013-0034405, filed on Mar. 29, 2013 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
An X-ray generally indicates a short wavelength electromagnetic wave having a wavelength of 0.01 nm to 10 nm and a frequency of 30×1015 Hz to 30×1018 Hz. X-ray photographing is one of radiographies of projecting and displaying an inner portion of an object to be inspected by high penetration power of the X-ray. As well-known, the X-ray involves an attenuation phenomenon depending on a material, a density, and a thickness of an object, such as Compton scattering, a photoelectric effect, or the like, during a process in which it is transmitted through the object. Therefore, the X-ray photographing projects and displays the inner portion of the object to be inspected on the basis of an attenuation amount of the X-ray accumulated during a process in which the X-ray passes through the object to be inspected. To this end, a dedicated X-ray system is used.
Recently, an X-ray image technology has been rapidly evolved as a digital X-ray image technology having various advantages such as a relatively high resolution, a wide dynamic area, easy generation of an electrical signal, simple processing and storing of data, and the like, instead of a traditional analog scheme using a film while being grafted onto a semiconductor field. A digital based image technology strongly reflects a clinically environmental demand such as an early diagnosis of a disease on the basis of excellent diagnosis ability of a digital image.
Therefore, a “digital mammography”, which is a breast dedicated X-ray photographing technology capable of detecting a lesion and micro-calcification for detection and an early diagnosis of a breast cancer by representing an internal structure of the breast corresponding to an object to be inspected as a high resolution image, using unique biological tissue contrast capability of the X-ray, has been introduced. The digital mammography has been rapidly spread due to unique characteristics such as image enlargement, a decrease in the number of times of photographing, an increase in a resolution, and minimization of exposure through adjustment of a luminance and a contrast ratio together with various advantages of the digital X-ray image technology.
A general mammography device mainly includes a support column having a lower end portion fixed to a bottom and having a vertical column shape and a C-arm or a device body installed on the support column so as to ascend or descend in a vertical direction and generally having a C shape or a shape similar to the C shape in which a central portion thereof is configured to be rotatable with respect to a horizontal axis. A generator irradiating an X-ray toward a lower end portion of the device body is mounted at an upper end portion of the device body, and a detector facing the generator is mounted at the lower end portion of the device body. A pressing pad that vertically and linearly reciprocates along an inner surface of the device body is installed between the generator and the detector.
In the mammography device as described above, when a subject is in a standing or sitting state at a photographing position, the device body ascends or descends and rotates with respect to the support column, such that a height and an angle of the device body are adjusted so that a breast of the subject is put at a target position on the detector. Then, the pressing pad moves toward the detector to press the breast. In this state, the generator irradiates the X-ray toward the breast and the detector, and the detector positioned behind the breast receives the X-ray passing through the breast to obtain an image.
That is, the detector generates an electric signal for each position that is in proportion to an amount of incident X-ray, and reads the electrical signal and position information and processes the read electrical signal and position information by an image processing algorithm, thereby making it possible to obtain an X-ray image of the breast for a corresponding angle. Then, the above-process is repeated while rotating the generator and the detector with the breast interposed therebetween, whereby the mammography device may obtain high resolution images for the breast of the subject at various mediolateral oblique view angles.
In a general mammography device having the above-mentioned photographing principle, a critical driving mechanical for minimizing discomfort of the subject and obtaining a high quality X-ray image is a pressing operation of the pressing pad and ascending or descending and rotating operations of the device body. Particularly, since the pressing pad applies direct pressure to the breast at the time of X-ray photographing, it is directly associated with pain and discomfort felt by the subject, and since the device body determines an accurate photographing position through ascent or descent and rotation, it is directly associated with quality of the X-ray image.
Here, the pressing pad presses the breast in order to photograph the breast in a state in which the breast is pressed for the purpose of separating a lump (a lesion or a portion at which the possibility of micro-calcification is high) looking like being overlapped with a mammary gland, or the like, from the mammary gland.
However, the pressing by the pressing pad, which is the largest pain felt by the subject, causes large discomfort. Further, when the subject moves due to the pain and the discomfort caused by the pressing of the pressing pad, the breast is out of a photographing position, such that an accurate X-ray image may not be obtained. Particularly, the pain due to the pressing of the pressing pad is mainly felt particularly at a distal portion (a portion adjacent to a nipple) of the breast of the subject, and the discomfort is further increased.